Our work has demonstrated a novel mechanism which may explain in the association of Kanagwawa-positive Vibrio parahaemolyticus (those strains which produce the Kanagawa hemolysin) with enteropathogencity. Our work has shown that Kanagawa-positive V. para adhere avidly to HeLa and to human fetal intestinal (HFI) cells in-vitro. Kanagawa-negative strains adhere poorly. We postulate that greater adherence by Kanagawa-positive V. para facilitates their colonization of the host gastrointestinal tract and allows expression of their enteropathogenic potential. In our studies, adherence by Kanagawa-positive V. para was reduced by treatments which affect bacterial surface carbohydrates and by the presence of crude V. para putative capsular polysaccharide in the incubation mixture. Thus, components of the V. para outer membrane, particularly capsular polysaccharide, appear to contain sites for binding to epithelial cells. We plan to identify these binding sites by: 1) the production, isolation and immunochemical characterization of outer membrane components of V. para, initially, capsular polysaccharide; 2) evaluating possible competitive inhibition by complex carbohydrates and enzymatic or lectin-induced alterations of the bacterial membrane; and 3) demonstrating interference with adherence by antiserum produced against material containing the putative binding site.